Anhydrous herbicidal concentrate



United. States. Patent 3,190 740 v ANHYDROUS HERBICIDAL CONCENTRATE Frederick J. Wolter, West Chester, Pa., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL,

a corporation of Delaware No Drawing. Filed Nov. 30, 1962, Ser. No. 241,177

1 Claim. (Cl. 712.6) This application is a continuation-in-part of copending aplication Serial No. 94,426, filed March 9, 1961; applications Serial No. 735,362, filed May 15, 1958, and Serial No. 550,749, filed December 2, 1955 .all abandoned; and Serial No. 313,044, filed October 3, 195-2, and issued as US. Patent No. 2,726,150.

This invention relates to herbicide concentrates and is more particularly directed to stable herbicide concentrates comprising herbicide particles dispersed in nonsolvent oils.

Concentrates of herbicides in oils have been known for many years. The herbicides in these concentrates have an unfortunate tendency to settle into dense deposits, and their crystal size frequently grows because of fluctuating storage temperatures. Such compositions can then be resuspended and diluted only with difiiculty and are inconvenient to spray because the large particles clog nozzles.

A superior oil concentrate having none of thesedisadvantages can be prepared according to this invention by suspending the active herbicide in a nonsolvent oil, adding lecithin, and then milling the composition until the parti: .cle diameter has been reduced to below microns.

The herbicideswhich can be formulated in this fashion are the substituted ureas and the substituted triazines. The

herbicidal ureas which are especially suited for formulaj 0.1% Weight of the active ingredient at voils tion are those of the formula i 0 R1 Qt- 11 where X is halogen, nis l, 2, or.3, R is methyl or ethyl, and

R is hydrogen, alkyl of one through four carbon atoms,

or alkenyl of one through four carbon atoms.

Illustrative of these ureas are:

(p-iodophenyl)-1,1-dimethylurea (3 ,4-dichlorophenyl -l-methyl-1-ethylurea (3 -bromo-4-chloroph enyl) -1, l-dimethylurea a 2,4,5 -trichlorophenyl) -1-methylurea (p bromophenyl)-1-methyl-1-isopropylurea 3 (p-chl orophenyl) -l,1-diethylurea 3- (2,4,5-trichloropheny1) -1 l-climethylurea 3- m-chlorophenyl) -1-methylurea 3- p-bromophenyl l -methylurea 3 (p-chlorophenyl) *1 -ethylurea 3 (-m-chlorophenyl) -1-methyl-1-is0propylurea 3,190,740 Patented June 22, 1965 Herbicidal triazines which can be'formulated according to this invention are those of the formula where X is chloro, methoxy, or methylrnercapto, and

R and R are alkyl of less than 4 caubons, or a (CH ),,OCH radical, where n is '2 'or 3.

Illustrative of these triazines are:

- 2,-4-bis(ethylamino)-6-met hylmercapto-l,3,5-triazine 2,4-bis (ethylamino )-6-ch-loro '1,3 ,S-triaZine 2,4-bis (isopropylamino -6-chloro-1,3 ,S-t-ri-azine 2-chloro-4-ethylamino-6-isopropylarnin0-1,3,5-triazine' '2-ethylamino-tisopropylamino-G-methoxy-l,3,5-triaziue 2-chloro-4-etl1ylamino-6-(3 methoxypropylamino)rl,3,5-

triazine The precise "amount of active ingredient to be used in the concentrates of this invention of course depend-s on the ultimate use of the compositionland is governed by such factors as the type of plant to be treated, climatic dissolving more active ingredient than this promote the growth of large crystals on storage. For the same reason, it is desirable that the oil have a-sulfonatable residue of no more than 20%, and be anhydrous.

Preferred oils are the petroleum hydrocarbon fractions obtained from paraffin-base petroleum, such asage, which make resuspension diflicult. 'Lecithinalso improves dispersion of the'active ingredients when the concentrates are diluted to use levels in oils.

It is essential that the use of Water and emulsifying agents other than lecithin be avoided in formulating the concentrates. Other emulsifying agents cause the formation of large crystals on long-term storage, and the presence of water tends to promote flocculation and makes the concentrates corrosive to metals and incompatible with other herbicidal oil formulations. The concentrates are therefore preferably anhydrous.

It is also essential that the solid ingredients of these concentrates have an average particle diameter of less than 5 microns. The concentrates are accordingly prepared by mixing the herbicide with the anhydrous oil and then grinding or milling the mixture in an ink or paint mill.

Alternatively, the dry ingredients can be ground separaitely in jet-impact or ball mills and then added to the o1 A highly preferred method, however, is to mix the herbicide with an oil and lecithin and then grind this mixture in a sand mill. A suitable apparatus and direct-ions for its use are disclosed in Hochberg US. Patent No. 2,581,414.

Such an apparatus can grind the concentrates to the desired particle size in from 15 to 45 minutes or more, depending on the initial particle size of the solids. The optimum time is best determined by inspection.

The oil formulations prepared according to these methods are highly stable and resist caking in storage. Prior to application, they can be extended with herbicidal oils or other carriers to give sprayable compositions which are also stable and resist settling. These diluted compositions are best used according to the methods prescribed for the active ingredient.

This invention will be more easily practiced by referring to the following illustrative examples:

Example 1 A mixture of 60 parts of crystalline 3-(p-chlorophenyl)-1,1-dimethylurea and 40 parts of lubricating oil is prepared. The oil is 21 Mid-Continent, solvent-treated petroleum oil, predominantly paraffinic, with a viscosity of 300 Saybolt Universal seconds at 100 F., and dissolves less than 0.1% of the urea at 30 C.

This mixture is milled by six successive passes through a Kent 3-r0ll ink mill with 4-inch rolls set at 0.001 to 0.0015 inch clearance. The substituted urea is uniformly dispersed as particles of less than 5 microns average diameter, with most of the particles being 1 mieron or less. This dispersion is in the form of a thick putty-like paste.

Equal parts of this paste and the lubricating oil are then mixed to give a pourable fluid composition containing 30% substituted urea. This concentrate has excellent shelf life and does not form a hard cake in the container upon storage.

Example 2 in a sand mill of the kind described in US. Patent 2,5 81,-

The resulting concentrate, after separation from the sand by centrifuging, is a thixotropic composition which does not settle, even after extended storage periods. Substantially all of the substituted urea particles are less than 5 microns in diameter.

Example 3 A slurry of 25%, 2,4-bis(ethylamino)-6-chloro-1,3,5- triazine in 75% Sovaspray Oil No. 2 is prepared.

Sovaspray Oil No. 2 is a dormant spray oil sold by the Socony Mobil Oil Company; it has a viscosity of S.U.S. at 100 F., a sulfonatable residue of 8%, and dissolves less than 0.1% of the triazine at 30 C.

The slurry is pumped to a continuous sand mill. The total residence time in the mill is about 20 minutes. The product contains particles of active material which are underS microns in diameter. The stable suspension so formed can then be diluted with a herbicidal oil and sprayed.

Example 4 Percent 2-ch1oro 4 isopropylamino 6 ethylamino 1,3,5-

triazine 30 Soya lecithin 1 Litetec mineral oil 69 (Liteteck mineral oil is a highly refined white oil sold by the Pennsylvania Refining Company. It has a viscosity of 50-60 S.U.S. at 100 F., and dissolves less than 0.1% of the triazine at 30 C.)

These components are mixed and milled in the same manner as described in Example 3.

Example 5 Parts 3-(p-chlorophenyl)-1,1-dimethylurea 30 Soya lecithin 3 Light mineral oil (viscosity 60 S.U.S.) 67

The oil is heated to remove all traces of water. The other ingredients are then added and the mixture is sand milled as described in Example 3.

The embodiments of the invention in which an exclusive property or privilege is claimed are:

An anhydrous herbicidal concentrate comprising 30 parts of 3-(p-chlorophenyl)-1,1-dimethylurea, 3 parts of lecithin and 67 parts of mineral oil, said urea having an average particle diameter of less than 5 microns.

References Cited by the Examiner UNITED STATES PATENTS 2,465,335 3/49 Burkhard l67-2 8 2,558,762 7/61 Kohr et al. 2,705,195 3/55 Cupery et al. 71-2.3 2,726,150 12/55 Wolter 712.6 2,891,855 6/59 Gysin et al. 71-2.5

FOREIGN PATENTS 465,153 4/37 Great Britain.

LEWIS GOTTS, Primary Examiner.

J. S. LEVITT, Examiner, 

